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> Rocker shaft to rocker arm clearance, Is there a spec?
Woody
post Jul 30 2013, 07:37 AM
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This is on a /4 2056. I've been chasing a noise that I believe is coming from the top end. It only occurs at idle and will completely disappear right off idle. It sounds like really loud valve clatter. Valves were recently adjusted and were not too far out of spec, Maybe a little bit tight. Noise was present before the valve adjust. On startup it is pretty bad, as the oil heats up it gets worse, but when the engine is at full operating temp after a 30 minute drive the noise is gone. I pulled the rockers and shafts to inspect for wear. The rocker shafts show some wear visually and measure at or just below spec at 19.94mm or .785". Haynes shows the spec at 19.95-19.97 mm. The shafts are not ovaled. The rocker arms measure out at 20.02 inside diameter or .788" and also are not ovaled. Does anyone know what the clearance is supposed to be?
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Woody
post Jul 30 2013, 03:31 PM
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ChrisFoley
post Jul 30 2013, 06:08 PM
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ALL the load is on one side of the shafts and the rocker bores.
If the shafts aren't scored and the dia difference is only .003 I can't see how there would be any problem.
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Woody
post Jul 30 2013, 06:09 PM
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There is some minor scoring but they still measure even across the shaft.
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Woody
post Jul 31 2013, 12:23 PM
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These are the rocker shafts. There is some wear on some of them. Two have grooves that will catch a fingernail.



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rick_cv
post Jul 31 2013, 12:32 PM
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Which pistons did you use for your 2056? Forged? Do a search for piston slap with forged pistons during warm up. Seems to be a common issue due to differing expansion rates between cylinders and piston.
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Woody
post Jul 31 2013, 12:35 PM
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This is a new noise though. It became noticeable a couple months ago. I've had the engine for a few years. I wouldn't think piston slap would all of a sudden show up.
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Woody
post Jul 31 2013, 02:19 PM
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Im gonna try some new adjusters. A couple of mine are pitted pretty bad.
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r_towle
post Jul 31 2013, 04:00 PM
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Solid spacers or are you still using the springs?
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Woody
post Jul 31 2013, 05:13 PM
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Springs for now.
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r_towle
post Jul 31 2013, 05:26 PM
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Pushrods tips?
Lifters?

Think about solid spacers while you are doing this...it helps keep the valve train consistent.
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Woody
post Jul 31 2013, 05:29 PM
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Just original adjusters. I'm going to replace the adjusters, rockers, shafts, and springs to see if it goes away. If it doesn't I'll take it apart. I built this engine when I was new to 914s.
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Woody
post Jul 31 2013, 05:30 PM
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Pushrods look good. Lifters are webcam. Valve lash has been consistent and hasn't changed much.
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r_towle
post Jul 31 2013, 05:37 PM
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solid spaces might be the right thing to do at this specific moment...kinda a pita to take it all apart again...and they are cheap.

rich
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r_towle
post Jul 31 2013, 05:38 PM
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do you have swivel foot adjusters or stock solid ones?
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Woody
post Jul 31 2013, 05:40 PM
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Solid adjusters. Who sells the solid spacers?
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r_towle
post Jul 31 2013, 05:42 PM
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http://www.europeanmotorworks.com/vw/type-4-rocker-arms.html
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Woody
post Jul 31 2013, 05:44 PM
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Thanks Rich. Gonna have to try that.
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r_towle
post Jul 31 2013, 05:47 PM
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I think of it like this.
You never really know what the rocker is going to do with springs.
You reduce that variable quite a bit when you use solid spacers...
Then you are getting exactly what you expect from the whole valve train.

Otherwise, with the rocker having the ability to move...you may not get the lift expected on each cylinder and that could make things run less than optimal.

For what, 4 bucks each...why not.
The rest of the parts you can get fairly cheap also..
New shafts, 16 bucks....just do that...no hesitation in my mind.

Rich
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Woody
post Jul 31 2013, 05:50 PM
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I need the car together for Saturday. I'll probably pull it back apart after this weekend.
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